The $SI$ unit of electric charge is $.........$

$A$ torch bulb is rated $5\,V$ and $500\,mA$. Calculate its $(i)$ power,$(ii)$ resistance,and $(iii)$ energy consumed when it is lighted for $4$ hours.

$(a)$ Derive the formula for the calculation of work done when current flows through a resistor.
$(b)$ One electric bulb is rated $40 \ W$ and $240 \ V$ and another is $25 \ W$ and $240 \ V$. Which bulb has higher resistance and how many times?

Mention the condition under which charges can move in a conductor. Name the device which is used to maintain this condition in an electric circuit.

What is the direction of conventional current?

Five bulbs are connected in a parallel circuit. If the second bulb blows out,what happens?